Cal. RTC § 6814

(a) The obligation of the successor shall be enforced by serving a notice of successor liability on the person. The notice shall be served in the manner prescribed for service of a notice of a deficiency determination, not later than three years after the date the board is notified of the purchase of the business or stock of goods. The successor may petition for reconsideration in the manner provided in Article 5 (commencing with Section 6561) of Chapter 5 of this part. The notice shall become final and the amount due and payable in the manner provided in that article except that no additional penalty shall apply if not paid when due and payable. The provisions of this chapter with respect to the collection of any amount required to be paid under this part shall apply when the notice becomes final.

(b) (1) If the board finds that a successor’s failure to withhold a sufficient amount of the purchase price to cover the amount owed by the former owner is due to reasonable cause and circumstances beyond the successor’s control, and occurred notwithstanding the exercise of ordinary care and in the absence of willful neglect, the successor may be relieved of any penalty included in the notice of successor liability.

(2) Any successor seeking to be relieved of the penalty shall file with the board a statement under penalty of perjury setting forth the facts upon which he or she bases his or her claim for relief.